The safe handling and disposal of regulated medical waste from various medical and health care facilities is a well-known problem. Of particular concern is the safe processing of contaminated needles, scalpels, and sharp metal or glass objects which have come into contact with the human body or bodily fluids. These items often include thermoplastic materials such as those found in syringes and tubing, vials of glass and other objects which have contacted bodily fluids.
Numerous environmental regulations have been enacted which prevent the use of conventional methods of waste disposal. On-site methods to render the infectious and medical waste safe have not proven to be practical or cost-efficient. Although the prior art discloses numerous examples of sterilization through the use of electronic beam radiation, gamma rays, heat, and even microwave energy, numerous problems still exist.
Sterilization by autoclaving, for example, does not solve the potential problems since sterilization is labor intensive and subject to human error. This sterilization method also does not change the dangerous nature of "sharps" materials such as needles and scalpels, and further does not render syringe tubes and parts unrecognizable or unusable.
The problems associated with used thermoplastic hypodermic needles and syringes are well known. These contaminated and dangerous handling materials resist decay and are often sought by illegal drug users. Past disposal techniques involve the requirement of medical facilities to cut the needle from the syringe body immediately after injection. This procedure, however, was discovered to spread disease through airborne aerosols caused by the mechanical sheering action. The contaminated needle tip and syringe would then still need to be handled and disposed of as a regulated waste item. More recent developments have lead to depositing the syringe and needle into a "sharps" container. The sharps container would then be delivered to an authorized facility in a costly "tracking" process.
A prior art device is capable of destroying the needle at the point of use through low voltage electric current. The needle is reduced along with all associated contaminants, at temperatures of incandescence by passing the current through the needle. This process leaves a sterile and incinerated residue, but suffers the drawback of not having the capability to render safe other commonly used materials, such as scalpels, glass, or leftover syringe parts. Other prior techniques handle sharp items by encasing the needles and scalpels in gels, resins, or thermoplastics. U.S. Pat. No. 4,662,516 to Baker Sr. et al., discloses such a technique. In Baker, et al., a thermoplastic bag with waste is melted at an autoclave temperature and is capable of encapsulating the medical waste. The product of this system, however, remains a hazardous material for handling purposes. The treated waste is recognizable and can be unsterile. The needles project from the solid mass, making them exposed and extremely dangerous. Further, autoclave sterilization depends on "wet heat" destroying microbial life by having the heat contact the life forms for a defined period of time. The autoclave sterilization process is not efficient when the waste is shielded by plastic bags or immersed in a liquefied or melted plastic.
An additional problem which these devices have not addressed, is the fact that infectious and hazardous fumes are discharged from the waste material as it is heated. These fumes contain chemicals from the thermoplastic syringes, various medications, body fluids, and other chemicals in addition to biological contaminants. U.S. Pat. No. 5,240,656 issued to Scheeres discloses a method and apparatus for treating contaminated plastic waste and discloses the use of a carbon filter for the purpose of removing any odors. The Scheeres system, however, does not handle the problem of filtering biological and viral contaminants within the fumes and does not disclose a method of directing air towards the filter.
The heating of several different waste materials at one time also creates the problem of non-uniform heating throughout the container. This leads to unpredictability with gas discharge. Several of the prior methods are also not capable of handling all types of medical waste. That is, many of the prior art systems are capable of handling syringes, but not capable of handling soft wastes such as gauze, tape and fabrics for sterilization purposes in a single on-site system.